Embodiments of the present invention relate to signal analyzers and frequency domain data production methods, and more particularly to signal analyzers and frequency domain data production methods for measuring a wide band input signal by acquiring time domain data of frequency bands of a periodic input signal and combining the frequency bands using correlations of common frequency bands between adjacent frequency bands.
Recently, the mainstream of the Internet, mobile phone, etc. is wide band communication with high volume and fast data communication. The transition to wide band communication requires that a signal analyzer for measuring signal quality of the data should have a wide band, also. As used herein, the signal analyzer is an apparatus that produces time and frequency domain data of a signal under test (SUT) and can analyze the signal under test from various viewpoints using the data.
US patent publication No. 2005/0021261 discloses a signal analyzer that has a plurality of frequency conversion paths to make wide band signal measurement possible as a technology to realize the wide band measurement. Specifically, the signal analyzer has first, second and third frequency conversion paths that acquire sets of time domain data of continuous different frequency bands. It increases the number of the data by interpolating the time domain data according to a bandwidth of a combined frequency band that is derived by combining the continuous different frequency bands, and then produces a set of frequency domain data with FFT calculation to be able to measure a wide band signal at a time.
The signal analyzer discussed above has the following issues.                (1) Because the above signal analyzer requires a plurality of frequency conversion paths to analyze a wide band signal, the signal analyzer becomes more expensive than the case to analyze a signal with a single frequency conversion path.        (2) Even if the plurality of frequency conversion paths is used for analyzing a wide band signal, there is a limit to be able to acquire a frequency bandwidth at a time because of limit of hardware process speed.        
To deal with the above issues, a signal analyzer and frequency domain data production method that allow measuring wide band frequency domain data of a signal under test is needed.